The processing power, memory capacity, available disk space, and other resources available to processing systems have increased exponentially. Computing resources have evolved to the point where a single physical server may host many instances of virtual machines and virtualized functions. Each virtual machine typically provides virtualized processors, memory, storage, network connectivity, and other resources. At the same time, high-speed data networks have emerged and matured, and now form part of the backbone of what has become indispensable worldwide data connectivity, including connectivity to virtual machine hosts. Improvements in virtualization will drive the further development and deployment of virtualization functionality. Further, rapid advances in electronics and communication technologies, driven by immense customer demand, have resulted in the widespread adoption of mobile communication devices. Many of these devices, e.g., smartphones, have sophisticated processing capability and rely on clocks of different frequencies to perform different processing tasks, e.g., decoding and playback of encoded audio files. In most of such devices, energy consumption is of interest, and reduced energy consumption is often a design goal.